TWI343050B - Method for determining optimum laser beam power and optical recording medium - Google Patents

Description

1343050 Π) DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a recording medium for determining the optimum laser beam power. [Prior Art] By using an objective lens of a high-order pupil mirror (NA) having a blue-violet light of 0.6 5 or higher at a center wavelength of 40 5 nm, the shortest recording mark length is short in the recorded optical recording medium. The length of the record mark in the DVDs. Although the shortest recording mark length in such an optical recording medium is as short as 0.15μηι to !J 0, 2μηι, depending on recording and modulation. When the length of the shortest recording mark reduced to this level reduces the amplitude of the optically reproduced signal, even if a wavelength equalization method similar to the length of the DVD is used, it is difficult to reproduce the information for the shortest mark and correspondingly longer. Marked signal. The wavelength interference between the marks becomes apparent. First, it's true that the signal needs to be recorded with the desired length of space between the markers. The high in the phase change optical recording medium can be achieved in the following manner; the pulsed laser beam is simultaneously applied to control the laser beam power according to three or more power parameters, and the start time and the completion time of the laser application of the power parameters . Here, there are three basic power parameters for laser beam applications: recording (spike) power (ρρ) optical recording

Corresponding to the wavelengths used for density CDs and regular-range filters, and the proximity of these lengths to control the duration of each cycle to 'erase-5- (2) 1343050 power (P e ), and bottom Power (P w ). The laser beam application period for Pp and Pb and the number of pulses for each power are optimized according to the mark length. For further precise control of the mark length, a laser application based on four powers of Pbs having different head pulses than other pulses can be utilized. These methods must find the best choice for each power level, which is based on how the disc is made. Different optical recording/reproducing devices may employ different optical recording conditions if the optimum recording conditions of the respective recording media are different. In addition, the laser beam power of the device can be varied due to the dust in the device being attached to the objective lens and/or due to the end of the life of the laser source itself. Since the recording conditions are marginally limited to high density and high linear velocity recording, it is increasingly necessary for the device to determine the optimum laser beam power. Even when a recording condition is recorded in advance in a reading area of a disc other than the user data area by simply forming a wobbling groove or groove therein or by changing its phase, the recording condition is simply read by using the apparatus and Recording information is still not necessarily the best record on the disc. Patent Documents 1 and 2 each disclose a method capable of optimally recording regardless of the difference in optimum laser beam power between different recording/reproducing devices. These methods determine the optimum recording power based on the characteristics called "modulation", which are reduced by the random pattern used for the amorphous portion by the random pattern of the recording mark and the range from the shortest to the longest space. The reflected signal voltage 'to be used for the crystallized portion of the longest mark' and the reflected signal voltage for the crystallized portion are divided by the enthalpy. These methods are used as the -6-(3) 1343050 method which is still capable of optimally recording with a recording/reproducing device using different optimum recording powers. And has a number of 値 and in the DVD ruler) -RE (can record information such as including with these HD DVD-R laser beam irradiation 30GB. In 〇) to 1 1 T (2T mark large response obtained in 2T The signal length equalization method of the mark mark is intentionally generated, and, in these problems. Meanwhile, in recent years, a rewritable optical recording medium using a format of a blue-violet laser beam aperture mirror 0.65 has been developed, achieving 15 GB in t inch. Storage capacity. As with BD (Blu-ray Beta Rewrite), these rewritable media are one type of their grooves. Examples of such media with 15 GB of storage capacity are HD DVD-ROM and HD-DVD; The rewritable media medium has as much storage capacity as basically, sharing the same format as *. Moreover, examples of rewritable media include those having two recording layers on the side for multiplying the storage capacity into the present invention. Such a medium is referred to as a one-sided double-layer recording medium in which the mark of the length range of 2T (the shortest mark of the longest mark) is arbitrarily recorded. The length is about 0.2 μm. If the reproduction is used from the photodiode ( PD) The modulation of the signal between the signal signals records the information, and the amplitude and mark space of the recorded signal are smaller than the amplitude corresponding to the other comparison numbers. Therefore, using a similar DVD, it is generated corresponding to some The signal of the close tag is unsatisfactory and thus a completely clear signal regeneration cannot be achieved. In rewritable media, the regeneration method is designed to solve this, for example, when a specific signal processing meter is used to increase the recording density and storage capacity. When drawing beyond the level of the level achieved by reducing the wavelength of the laser beam, use appropriate PRML to compensate for the amplitude margin associated with reduced resolution (4) (4)

1343050 Reduced, so that it can have a stable high density of regeneration. Partial PRML means that the waveform equalization technique and the signal processing technique are removed during the recording or regeneration process to remove the shape distortion to change them to have the relevant shape number. The processing technology is based on the recording modulation code. It is used by using etc. and selecting a modulation method that seems to be more appropriate for ETM (eight to twelve modulation) from a regenerative signal containing data errors. As a measure of the quality of the evaluation mark, in addition to the jitter of the CDs, a measurement called PRSNR is also used to simultaneously represent the S/N (signal ratio) of the reproduced signal and the real p|PR waveform (when estimating the disc The linearity required for the bit error rate. The correlation signal is processed by a specific signal, and the difference of the reproduced signal is normalized as the PRSNR. When the above-mentioned regeneration method is required, the beam power is unsatisfactory in the conventional method; It is the amount of the center of the amplitude of the signal of the longest mark deviating from the shortest center of the mark, indicating the measurement of the symmetry of the reproduced signal from the shortest and longest marks. Therefore, the use of modulation as the main quantity is not enough. And change, a better way. In addition to the above-mentioned conventional methods, some of the most well-known methods of decision-making use asymmetry as the quality assessment of the mark, although depending on the recording method used, but with the greatest possible response The waveform of the wave of the wave regenerative signal, and the redundant data sequence of the signal waveform. It is called the recording code of the DVD s. The PRNSR is enough to waveform and theoretically One of the measurements is the conventional method between this signal and the actually determined optimal lightning, that is, the amplitude of the corresponding signal amplitude. It is necessary to consider the measurement of the laser beam power. In this case, in the low power at which the signal amplitude of the sufficient amplitude of * 8 - (5) (5) 1343050 is not obtained, the asymmetry enthalpy becomes zero. However, this does not mean that unless the optimal 値 of the asymmetry is zero, sufficient recording quality cannot be achieved, and the asymmetry 値 is preferably close to zero. When the asymmetry 改变 changes due to a reading error in the recording/reproducing device, it is difficult to specify the asymmetry 此 in this example. Moreover, the conventional method is intended for a single-layer recording medium and has not previously been applied to a single-sided double-layer recording medium. One of the two information layers of the single-sided double-layer recording medium (one closer to the laser beam irradiation side) has a different characteristic from the information layer in another information layer or a single-layer recording medium: it must make the light into other information. Light can be received and overwritten by a phase change between amorphous and crystalline states by absorption of light. Ideally, the information layer closer to the illumination side of the laser beam than the other information layer needs to have a transmittance of 50% or more. In this case, the information layer needs to reduce the thickness of the recording layer and the reflective heat dissipation layer that serves as reflected light and helps to dissipate heat. Therefore, the optimal recording condition range of this information layer is narrowed to a level not seen in the prior art. In particular, the range of optimal laser beam power is narrowed due to reduced heat dissipation efficiency and absorption efficiency. Therefore, a new method for determining the optimum laser beam power to be performed by the recording/reproducing device is required when recording on a single-sided double-layer recording medium, especially when recording on an information layer closer to the irradiation side of the laser beam. . (Patent Document 1) Japanese Patent (JP-B) No. 3,296,642 (Patent Document 2) Japanese Patent (JP-B) No. 3124721 SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, and to provide a record that can be ignored / -9 - (6) 1343050 . The method of determining the optimum laser beam power for recording the optimum recording power between the reproducing devices at the optimum recording power on the optimum recording medium, and the optical recording medium to which the method is applied, Therefore, the present invention has been completed. * The present invention is based on the findings of the present inventors, and the method for solving the above problems will be described below. <1> A method of determining an optimum laser beam power for a single-sided double-layer optical recording medium having first and second information layers, the φ method including when on a recording medium When the number of overwrite cycles is a predetermined chirp, the optimum laser beam power is determined according to a predetermined characteristic, wherein the method is implemented by using an optically variable optical recording/reproducing device, and the first information layer is smaller than the second information layer Closer to the laser illumination side. <2> The method of determining the optimum laser beam power according to <1>, wherein the recording power is optimized according to the modulation of the longest mark between the marks of various lengths, and the fixed recording power is used as a fixed At the same time, the power is erased according to the PRSNR. # <3> A method of determining an optimum laser beam power according to one of <1 > and <2>, wherein the number of overwrite cycles on the recording medium is 1. <4> The method of determining the optimum laser beam power according to one of <1> and <2>, wherein the number of overwrite cycles on the recording medium is 10, which is the stability characteristic. *<5> The method of determining the optimum laser beam power according to any one of <2> to <4>, wherein the point at which the ratio of the maximum PRSNR or PRSNR change to the erasing power is equal is determined. Good to remove power. <6> -10- (7) (7) 1343050 method of determining the optimum laser beam power according to any of <2> to <5>, wherein the optimum erasing power is determined such that the asymmetry Have a predetermined order. A method of determining an optimum laser beam power according to any one of <1> to <6>, wherein in the state in which the information layer is recorded after the optimum laser beam power of the first information layer has been determined, The optimum laser beam power is determined for the second information layer. An optical recording medium comprising: information required to perform a method of determining an optimum laser beam power according to any of <!> to <7>. <9> An optical recording medium comprising: - recording sensitivity correction factor 'this factor enables the method of determining the optimum laser beam power according to <7> to be determined in the state in which the first information layer has been written The optimal laser beam power of the second information layer. <1> The optical recording medium according to <7>, wherein the reflectance of each of the first and second information layers corresponding to the user material area is 3% to 6%. According to the method of determining the optimum laser beam power of the present invention, the optimum recording power can be recorded on the optimum recording medium irrespective of the change in the optimum recording power between the different recording/reproducing devices. Moreover, the optical recording medium of the present invention is suitable for use in the method of the present invention for determining the optimum laser beam power. [Embodiment] The present invention is particularly related to a technology for recording or reproducing information using a laser beam having a wavelength of 405 nm and an objective lens having an NA of 0.65, and providing a single-layer double-layer optimum recording. The method of the best laser beam power for the media. The optimum laser beam power used in this paper is based on three power parameters: -11 - (8) 1343050 _ recording power (Pp), erase power (Pe), and bias power (Pb). An additional power parameter (-Pp2) is used when controlling the recording power according to 2 or more parameters. - The method used to determine the optimum laser beam power basically uses "modulation" as the characteristic 値, which subtracts the reflected signal voltage for the longest mark by the reflected signal voltage for the mark space, ie The amplitude of the reflected signal for the longest mark, and is obtained by dividing the reflected signal voltage (φ reflected voltage) for the mark space by the last 値. In the recording/reproducing apparatus, the respective parameters are changed in such a manner that the PRSNR, the error rate, the modulation, and the asymmetry fall within a predetermined range. It should be noted that the device is not limited to those utilized in the market: any device capable of evaluating the characteristics of the media can be used. At this point, the pulse generation condition (hereinafter referred to as "write strategy" (see Fig. 1)) is adjusted in terms of the pulse duration, whereby the optimum condition is determined in advance. Here, the modulation (m) is defined by the following equation:

#调变=(Reflected signal voltage for 11T mark)-(Reflected signal voltage for 11T mark space)/(Reflected signal voltage for ΠT mark) When determining optical laser beam power, use The determined write strategy " slightly, Pe/Pp, and bias power Pb, record 'information' at various recording powers (Pp). The recording area reserved for determining the optimum laser beam power is the test writing area radially placed toward the inside of the disc, rather than being protected for the user's user data area. In this attempt, the recording/reproducing apparatus is capable of performing measurement/reproduction of -12-1343050 (9) various recording powers (pp) of the lowest to highest range for the measurement of modulation (m)' and storing the measurement results in Data processing in L SI. Modulation (m ~ ) depends on the recording power (pp ) as shown in Figure 2. Here, the predetermined enthalpy of using Pe/Pp and Pb/Pp is used to determine the power (Pe) and the bias power (Pb). In the conventional method, γ 値 (γ ) : ( γ ) = (dm / dPp ) x ( Pp / m ) is calculated. Then use this equation to set the target γ( ytarget ) 〇 φ not to select the target γ ( Ytarget ) from the region where the modulation (m ) reaches a higher level and the modulation increase rate is large (ie, the region where the recording power level is significantly lower). Before the modulation (m) reaches a higher level, Ytarget is selected from the region corresponding to the modulation (m) 对应 of the range of 0·4 to 0·5 provided by the modulation flush at 0·6 to 0.65. good. Therefore, even when the absolute enthalpy for recording power between recording devices is different, since the dependence of the modulation curve on the recording power is maintained, the same Ytarget can be obtained almost.

D Φ is the optimum recording power (Ppo) by doubling ptarget (corresponding to the recording power of ytarget) by a factor (P). The factor (p) is chosen to achieve the best characteristics. Thus, even when the optimum recording power differs between different recording devices, the optimum recording power (the recording power capable of obtaining the optimum recording characteristics )) can be selected. Conventionally, this method has been applied to single-sided single-layer recording media, but when looking at single-sided double-layer recording media, the reduction of the optimal characteristic range means that the range of optimal recording conditions is reduced; therefore, if only based on If you choose the best recording power, then some features do not necessarily use the best. -13- (10) (10) 1343050 Some rewritable recording media undergo substantial changes in characteristics after each overwrite cycle. The current state requires a high recording speed (4x, 83⁄4 ' or 12x reference linear velocity (lx)), and after the first recording cycle (ie the first record on the non-receiving zone) and the 1〇 overwrite cycle After comparison, after the first overwrite cycle (i.e., after 2 recording cycles), phase change optical recording media (even those with a one-sided single layer configuration) tend to have a significant reduction in characteristic 値. However, depending on what parameters are used in the loop, there is an example of not obtaining the best recording power (even if the next overwrite is taken into account). Usually, the optimum recording power is determined after a 1 〇 recording cycle. In addition to the method of determining the optimum recording power using the above-mentioned characteristic called modulation, there is also an asymmetric method. In this paper, "asymmetry" is defined as follows: Asymmetry = (I11H + I11L-12H-12L) / ( 2(I11H-I12L)) Asymmetry 値 is equal to zero. Even when a high-profile change is successfully obtained, depending on the recording power condition, an asymmetry that largely deviates from zero still causes an error increase. Therefore, it is not desirable to optimize the recording power based only on this characteristic. Because depending on the recording conditions, it is possible that the misalignment is not close to zero at the same time. In particular, write strategies and erase power are more dependent on asymmetry. When considering the characteristic 称作 called PRSNR, it is difficult to determine the optimum recording power based on modulation or asymmetry, as in the conventional example. However, modulation is a necessary feature. The PRSNR increases as the amplitude of the signal for the longest mark increases, and the difference in signal amplitude is as large as possible between different marks. The modulation power (Pp) is determined using modulation. Moreover, when the modulation is determined according to "γ" -14- (11) 1343050 It must be noted how to select the "dPp" in the equation (γ) = (dm/dPp) Pp/m). When "dPp" is allowed to have O.lmW's in the recording power region where the modulation curve starts to be flush, (γ) chopping cannot draw a curve as shown in Fig. 2 (see Fig. 3). In the example of the curve shown in Fig. 3, if the recording device selects γΠ as shown in the drawing of the recording medium in advance, the result is that two Ptarget値 (Ptl and Pt2) are generated. In this case, the result of selecting Pt2 Ptarget値 is to select an optical recording power higher than Ppol. If the recording power is too high, the characteristic 値 is lowered, resulting in that the recording power is not optimal. Moreover, even when the characteristics 値 still fall within their optimum, it can be further reduced after 100 overwrite cycles, 1000 overwrite cycles, and the like. In this case, γ値 can be reduced to minimize the variation of the modulation enthalpy by using a large dPp 値 (e.g., 〇.5mW large) or by approximating the modulation curve in a quadratic function. The multi-approximation technique using, for example, the following formula is used to make the obtained curve as completely as possible with the original modulation curve.

K, n*Pw + k, n*PwA2 + k, n*PwA3+k, ...n*PwAn + aO where "η" is 2 or more, and "k" and ''η" are factors. When it is found that the optimal recording power that has been properly determined exceeds the maximum power of the recording device, 'only need to enable the device to record at that maximum power. The optimum laser beam power will be described in detail in the example. An example of a rewritable single-sided double-layer optical recording medium. 値时动,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Adding at least one metal element selected from the group consisting of Bi, Cu, In, etc., in an amount of 1343050% improves the regeneration stability of the first information layer. Preferably, the second reflective layer 4d is an Ag alloy other than Ag. It is made to have a thickness ranging from 10 nm to 200 nm. Preferably, the upper protective layers 2c and 4c disposed adjacent to the information layer are made of materials capable of increasing the environmental durability of their recording layers, which are Transparent and having a higher melting point than the recording layer. In a single-sided single-layer phase change optical recording medium, ZnS-SiO 2 is often used. In this example, the optimum ratio of ZnS to SiO 2 (ZnS:SiO 2 ) is known to be 80: 20. However, the first reflective layer 2d of the single-sided two-layer phase change optical recording medium is more than one side The first reflective layer of the single-layer optical recording medium is thin. Therefore, the heat dissipation ability is lowered, so that the establishment of the amorphous phase becomes difficult. Therefore, it is preferable that the first upper protective layer 2c uses a material having the highest thermal conductivity as possible. It is preferred to use an oxide having a higher heat dissipation capability than ZnS-SiO 2 . Particularly suitable examples are ZnO, Sn 〇 2, A12 Ο 3, Ti 〇 2, I Π 2 Ο 3, Mg Ο, Zr Ο 2, TaO, Ta Ο 5 , and Nb 205 . Etc. metal oxide. It should be noted that when Zn-SiO 2 is used for the upper protective layer 2c and Ag is used for the reflective layer 2d, it is necessary to provide a vulcanization preventing layer to prevent Ag in the reflective layer and the upper protective layer. S is a chemical reaction. For example, a mixture of Ti02 and TiC can be used for this layer. The thickness of the first upper protective layer 2c is preferably in the range of from 10 nm to 35 nm. As is conventionally known, the second upper protective layer 4c is Made of ZnS-Si02. When Ag or Ag alloy is used for the second reflective layer 4d, the thickness ranges from 2 nm to An interface layer of 4 nm and made of, for example, TiOC is disposed between the second upper protective layer 4c and the second reflective layer 4d. -17-(14) in each of the lower protective layers 2a and 4a

The optimum ratio of ZnS to SiO 2 (ZnS:SiO 2 ) is 80:20. The heat diffusion layer 2e has a high thermal conductivity for rapidly cooling the first recording layer 2b which has been irradiated with the laser beam light. Moreover, the thermal diffusion layer 2e preferably absorbs light at a wavelength of the applied laser beam, that is, the thermal diffusion layer 2e allows the laser beam and has a refractive index as high as 2 or more, which enables a higher refractive index. Record and regenerate information. For example, InZnOx or InSnOx is preferred. Further, the tin oxide content present in InSnOx is preferably in the range of from 1% by mass to 10% by mass. If the tin oxide content falls outside this range, it will result in a decrease in thermal conductivity and transmittance. The content of Ιη 2 03 present in InZnOx or InSnOx is preferably about 90 mol%. The range of the thermal diffusion layer 2e is preferably from 10 nm to 40 nm. Further, Nb205, Zr02, and Ti02 are also preferable materials. It is necessary that the first substrate 1 sufficiently allows laser light to be applied for recording and reproducing information, which is a material known in the art. That is to say, glass, ceramics, resins, etc. are used. In particular, resins are preferred in view of plasticity and cost; examples include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, propylene-styrene copolymer resin, polyethylene resin, polypropylene resin, tantalum resin , fluororesin, ABS resin, and urethane resin. However, polycarbonate resins such as polymethyl methacrylate (PMMA) and acrylic resins are preferred in view of excellent plasticity and optical properties and cost. On the surface of the first substrate 1 to kill the first information layer 2, there are concave and convex patterns, such as spiral or concentric grooves. This pattern is usually formed by, for example, plastic injection molding or photopolymerization. The thickness of the first substrate 1 is preferably from 590 μm to 610 μm, and the -18-(15) (15) 1343050 and the second substrate 5 are formed of the same material as the first substrate 1. Ideally, the intermediate layer 3 absorbs less light at the wavelength of the laser beam applied to record and reproduce information and is made of a resin in view of plasticity and cost; for example, a UV curable resin, a slow curing resin, and Thermoplastic resin. As with the first substrate 1, the second substrate 5 and the intermediate layer 3 may have a concave and convex pattern such as a groove formed by plastic injection molding or photopolymerization. The intermediate layer 3 is for distinguishing the first information layer 2 from the second information layer 4 for optical isolation during recording or reproducing information, and preferably has a thickness ranging from ΙΟμιη to 70 μm. An intermediate layer thickness lower than ΙΟμιη may cause crosstalk to occur more likely between the information layers. Conversely, an intermediate layer thickness greater than 70 μm causes a spherical aberration while recording or reproducing information from the second recording layer 4b, thus causing recording and The regeneration operation is difficult to perform. The reflectance of each of the information layers 2 and 4 in the single-sided double-layer optical recording medium ranges from 3.5% to 8%. If the reflectance is less than 3.5%, the recording/regeneration device may not be able to achieve laser focus and groove tracking. Although there is no upper limit on the reflectance, about 8% is a practical limit, and the lower limit is 4% or more. Although it is easy to increase the reflection ratio of one of the information layers 2 and 4, if the reflectance of the other layer is too low, the difference in reflectance between the information layers 2 and 4 becomes too large. Therefore, when switching from one of the information layers to another, it becomes difficult to focus the laser beam on another information layer. Therefore, it is preferable that one of the information layers has a reflection ratio of 1.5 times or less of the other layer. In this embodiment, at least one read-in area of the optical recording medium (area closer to the center of the disc than the user data area) and the readout area (on the circumference of the disc -19 - (16) (16) 1343050 The area) is preformatted with information on the recording conditions used for the recording processing to be described later, that is, the setting for determining the optimum recording power and the optimum erasing power. The term "pre-formatted" means a slot previously formed on a disc, as in ROMs. A method of manufacturing an optical recording medium will be briefly described below. The manufacturing method includes a film deposition step, an initialization step, and a bonding step, and is generally performed in this order. In the film deposition step, the first lower protective layer 2a, the first recording layer 2b, the first upper protective layer 2c, the first reflective layer 2d, and the thermal diffusion layer 2e are successively deposited to form a concave and convex pattern On the surface of a substrate. For the sake of convenience, the article formed by the first information layer 2 deposited on the first substrate 1 as described above will be referred to as a "first recording member". Further, the second reflective layer 4d, the second upper protective layer 4c, the second recording layer 4b, and the second lower protective layer 4a are successively deposited on the surface of the second substrate 5 which forms the concave and convex patterns. For the sake of convenience, the article formed by the second information layer 4 deposited on the second substrate 5 as described above will be referred to as a "second recording member". The above layers are deposited by sputtering. In the initial initialization step, the first and second recording members are irradiated with a laser beam for initialization and crystallization of the entire surface thereof. In the initializing step, the recording member may be separately initialized before being joined together; or the second recording member may be initialized first, then joined to the first recording member and the first recording member is initialized. In the joining step, the first and second recording members are joined together by the intermediate layer 3 interposed therebetween. For example, after coating one of the thermal diffusion layer 2e and the second lower protective layer 4a-20-(17) 1343050 with the UV curable resin, the first and second recording members are joined together, the thermal diffusion layer 2e and the second lower protective layer 4a face each other, and then the UV curable resin is cured by UV irradiation. In this way, the first and second recording members ‘ are combined by the intermediate layer 3 to form a one-sided double-layer optical recording medium. FIG. 5 illustrates an example of the optical recording/reproducing device 20. The optical recording/reproducing device 20 includes, for example, a spindle motor 22 for rotating a light φ disc 15 of a one-sided double-layer optical recording medium according to an embodiment of the present invention; an optical pickup device 23; and a seek motor 21 for driving The optical pickup device 23 moves to the direction of the slider: the laser control circuit 24: the encoder 25: the drive control circuit 26; the regenerative signal processing circuit 28; the buffer RAM 34: the buffer manager 37: interface 38; the flash memory board 39; 40; and RAM 41. It should be noted that in Figure 5, the arrows indicate the flow of sexual signals and information, not all connections between blocks. It should also be noted that in the present embodiment, the optical disk device 20 is assumed to be capable of being recorded on a single-sided multilayer optical disk. • Based on an output signal (multi-photoelectric conversion signal) from an optical receiver or a photodiode (PD), the reproduced signal processing circuit 28 requires, for example, a servo signal (eg, focus error signal and tracking error signal), address information, synchronization Information, RF signals, modulation information, gamma information, asymmetric information, and amplitude information of the total signal. The servo signal thus obtained is output to the drive control circuit 26, the address information is output to the CPU 40, and the synchronization signal is output to the encoder 25, the drive control circuit 26, and the like. The reproduced signal processing circuit 28 performs decoding and error detecting operations on the rf signal. If any error has been detected, the error -21 - (18) 1343050 error correction processing is performed, and the RF signal is stored as the reproduced data in the buffer RAM 34 through the buffer manager 37. The address information stored in the reproduced data is output to the CPU 40. The reproduced signal processing circuit 28 transmits the modulation information . , γ 値 information asymmetry information, amplitude information of the total signal, and PRSNR 値 to the CPU 40. The drive control circuit 26 generates a drive signal for driving the drive unit based on the servo signal received from the reproduced signal processing circuit 28, and outputs it to the optical pickup device 23. To perform tracking control and focus control. The drive control circuit 26 generates a drive signal for driving the seek motor 21 as indicated by C P U 40 and a drive signal for driving the spindle motor 22. The drive signal is output to the corresponding motor (the seek motor 21 and the spindle motor 22). The buffer RAM 34 temporarily stores, for example, information (record data) to be recorded on the optical disk 15 and data (regenerated data) reproduced from the optical disk 15. The data input or output buffer ram 34 is managed by the buffer manager 37. As indicated by the CPU 40, the encoder 25 retrieves the record data stored in the buffer RAM 34 through the buffer manager 37, modulates the data, and adds an error correction code to the data to generate a write for writing to the optical disk 15. signal. The write signal thus generated is output to the laser control circuit 24. The laser control circuit 24 controls the laser output power of the semiconductor laser LD. For example, when recording, the driving characteristic of the semiconductor laser L D is generated by the laser control circuit 24 in accordance with the writing signal, the recording condition, and the driving signal for driving the semiconductor laser LD. The interface 38 is for interfacing with a high-end device 90 (such as a personal computer), and follows an interface such as AT API (High-Level Technology Add-on Packet Interface), SCSI (Small Computer System Interface), and Standard interface such as USB (Universal String • Column Bus). - The flash memory 39 stores various programs written in the code that the CPU 40 can decode, such as a program for determining the optimum power, the emission characteristics of the semiconductor laser LD, and the like. The CPU 40 controls the operation of the above φ unit based on the program stored in the flash memory unit 39, and stores the data required for the operation control in the RAM 4 1 and the buffer RAM 34. The processing (recording processing) performed by the optical disc device 20 when receiving a command from the high-order device 90 will be explained with reference to Figs. The flowcharts shown in these figures correspond to a series of processing algorithms executed by the CPU 40. When receiving the record request command from the high-order device 90, the header address of the program in the flash memory 39 corresponding to the flowcharts of FIGS. 6 and 7 is set in the program counter of the CPU 40, and then the recording process starts. . • In the initial step (step 401), the drive control circuit 26 is instructed to rotate the optical disk 15 at a predetermined linear speed (or angular velocity) and to notify the regenerative signal processing circuit that the command has been received from the higher order device 90. In the next step (step 403), the index location is retrieved from the record request command, and it is determined from the address whether the target record layer is the first record layer 2b or the second record layer 4b. In the next step (step 405), information is retrieved from the slot storing the optical disc 15 relating to the recording condition, thereby calculating "ε", which is the ratio of the erasing power (Pe) to the recording power (Pp) (=Pe/Pp) ; and "p", which is an amplification factor for calculating the optimum recording power for -23-(20) (20) 1343050. The obtained enthalpy is stored in R A Μ 4 1 . In the next step (step 4〇7), the initial chirp for recording power (Ρρ) is set and sent to the laser control circuit 24. In the next step (step 409), the erase power (p e ) is calculated in such a manner that the ratio of the erase power (Pe ) to the recording power (P p ) is equal to "ε " and is sent to the laser control circuit 24. In the next step (step 411), the CPU 40 instructs the laser control circuit 24 and the optical pickup device 23 to record the test data in the test write area previously set in the target recording layer. It should be noted that in this example, although various marks having a length ranging from 2T to 11T are randomly recorded, the frequency at which they occur is determined in advance. Therefore, the test data is recorded in the test write area by the laser control circuit 24 and the optical pickup device 23. Before the test is written, Pe can use the laser beam to fully illuminate the test write area once. This can be done regardless of the presence of the mark, because in some optical discs, the crystallization area (non-recording area) produces different reflected signal voltages, that is, the voltage sometimes fluctuates greatly in some areas of these areas, so accurate signal regeneration is not may. The number of times the test write cycle needs to be set; here, the test write area is overwritten 10 times. In the next step (step 413), it is determined whether the test write has been completed. If it is decided that the test write has not been completed, the decision is rejected and processing continues to step 4 1 5 . In step 4 15 5, the previously set 値 (change Δρ ) is added to the recording power (Ρρ), and the processing returns to step 409. -24- (21) 1343050 Until the decision of step 413 is accepted, the loop of steps 4〇9', step 411, step 413, and step 415 is repeated. Once the test write is completed with the previously set/different recording power (Pp), the decision made in step 4 1 3 is accepted and processing proceeds to step 417. In step 417, the test data recording test write area is read by the reproduced signal processing circuit 28 to obtain the modulation information, and the actual calculation γ 値. In the next step (step 419), as shown in the example of Fig. 2, φ is used to establish the relationship between the recording power (Ρρ) and the modulation (m) and γ値 with the modulation information. In the next step (step 421), the recording power (Ptarget) is calculated using the map from the recording power (ρρ) vs. γ値 and the ytarget (target γ値) of the map of the recording power (Pp) vs. modulation (m). .

In the next step (step 423), use the equation Pp〇 = P X

Ptarget calculates the best for recording power (defined as "Pp〇"). In the next step (step 43 1), the recording power is set to Pro (optimal 値) and sent to the laser. Control circuit 24. In the next step (step 43 3), the initial 用于 for "ε" is set. In the next step (step 43 5), 値' ' of (ε X Pro) is calculated and sent to the laser control circuit 24 as Wipe Power (Pe) ° In the next step (step 4 3 7), the CPU 40 indicates that the test data is recorded in the test write area set in advance in the target recording layer. The test data is recorded by the laser control circuit 24 and the optical pickup device 23 in the test write -25-(22) 1343050 area. In the next step (step 439), it is determined whether the test write-in has been completed. If it is determined that the test write has not been completed, the decision is rejected and the process continues. Proceed to step 441. In step 44 1, the previously set 値 (change Δε) is added to "ε", and the process returns to step 435. Until the decision of step 439 is accepted, the loop of step 43 5, step φ 437, step 439, and step 44 1 is repeated. Once the test write is completed with a different ε set in advance, the decision made in step 439 is accepted and processing proceeds to step 443. In step 443, the test record test write area is read by the reproduced signal processing circuit 28 to obtain the PRSNR information. In the next step (step 445), as shown in the example of FIG. 8, the relationship between the erase power (Pe) and the PRSNR is established using the PRSNR information. • In the next step (step 447), the power is removed from the peer (Pe). The map of vs.PRSNR (see Figure 8) calculates the 用于 used to erase power (Pe). The obtained erase power 値 (Peo ) is regarded as the best 作用 for the erase power (Pe ). It should be noted that the maximum PRSNR 値 is 15 or more. In the next step (step 50 1), the CPU 40 instructs the drive control circuit 26 to focus the spot light spot to the target position. In particular, the indication drive control circuit 26 forms a spotlight spot near the target position corresponding to the designated address. The seek operation is performed in this way. If you do not need to find a job, skip this step. -26- (23) 1343050 In the next step (step 5 03), set the recording conditions. This recording power is set to Ppo and the erasing power is set to Peo, that is, the optimum chirp is set for both recording power and erasing power. In the next step (step 5〇5), information logging is allowed. Under the optimum recording conditions, the user data is recorded at the designated address via the encoder 25, the laser control circuit and the optical pickup device 23. The optimum laser beam power method that determines the following steps will be described in detail. The rewritable optical recording medium using the phase change material undergoes a change in recording characteristics after each overwrite cycle. If the characteristic change is small enough to be able to meet the 値, there is no real problem. However, if the characteristic 値 falls to near the standard 几次 and the optimum laser beam power range after several overwrite cycles, it becomes problematic. Figure 9 illustrates that the PRSNR of the first information layer 2 changes with a recording cycle from 〖to 1 1 (i.e., an increasing number of overwrite cycles from 1 to 1 。. It is apparent from Fig. 9 that the first overwrite cycle PRSNR Decrease, if the standard 値 is set to 15 or higher PRSNR 値 close to the standard in Figure 9. The recording power and erase power above or below the result of successfully obtaining Figure 9 cannot meet the standard 値. , which usually results in a narrow optimal laser beam power range of O.lmW. In this case, of course, it is assumed that the characteristic is not seen when the next overwrite cycle is followed, and the most recorded is set after the first overwrite cycle. The power is better. If the characteristic 値 is greatly reduced after the first overwrite cycle, the optimal erase power range is narrowed. Therefore, the optimization of the erase power is particularly important. Considering this fact, according to the first overwrite cycle The obtained 値 determines the optimal laser beam power. When it is at the first overwrite cycle, it is the result, 24, the square learns how the foot ring becomes smaller), then the figure is full, such as the ring Zhong Jia Ji, then its heavy special -27- (24 (24) 1343050 The best recording power and the best erasing power show little or no change, and the characteristic 値 changes quite small, and the optimal laser is determined according to the characteristics obtained after the 1 〇 overwrite cycle. The power is better. This is because the variation in characteristics obtained after the first overwrite cycle in some optical recording/reproducing devices is large, and an appropriate defect is not obtained. In the single-sided double-layer optical recording medium, there is a difference in recording sensitivity between the first information layer 2 and the second information layer 4 disposed at a position farther from the laser irradiation side than the first information layer 2. In some optical recording media of these optical recording media, the recording sensitivity of the second information layer 4 can be determined depending on whether or not the first information layer 2 has been written or written. Therefore, it is important to optimize the laser beam power for each information layer. To achieve this, in the case of the first information layer 2, the dependence of the modulation on the recording power during the 10 overwrite cycle is investigated as described above to calculate γ t a r g e t, P t a r g e t, " ε ", and " ρ ". Thereafter, the optimum erase power is determined based on the characteristics obtained after the first overwrite cycle or the 10 overwrite cycle, and then the last 用于 for "ε" is decided. (when ε = ε '). Moreover, test writing is performed on the read-in area (area closer to the center of the disc than the user data area). Next, the second information layer 4 determines the optimum beam power and optimum conditions on the other test write area of the outermost circumference of the disc that is closer to the user data area. Before the test is written, it is preferable to write the first information layer 2 in advance on the area of the test write area corresponding to the radiation position. However, in this case, it takes time for the pickup to find the designated test write area. To avoid this, the media manufacturer records in advance a correction factor for correcting the change in the optimum recording power -28-(25) (25) 1343050 of the second information layer 4 due to writing to the first information layer 2. Thus, while the first information layer 2 remains unwritten, the ytarget, Ptarget, "ρ", and "ε" of the second information layer 4 can be determined to determine the optimal laser beam power. The tricks to determine the optimal laser beam power are ^target, Ptarget, "ρ", "ε", and asymmetry. In a single-sided, two-layer optical recording medium, these defects are recorded on each layer of their information layer. Moreover, the recording sensitivity correction factors for the first and second information layers 2 and 4 are recorded. In particular, these defects are recorded in the form of embossed grooves formed on designated areas called read-in areas. Further, after the error rate example can be used, the present invention will be described with reference to examples, but these examples are not intended to limit the present invention. Using the strategy shown in Fig. 1, the recording/reproduction speed is set to 6.61 m/s, and reproduction is performed. The power is set to 0.7 mW. Use DVD Sprinter (single-wafer sputtering equipment, manufactured by Balzers). Note that '1" recording cycle means "9 overwrite cycle" and "2 record cycle" Said "1" Write cycle" (Example 1) As the first substrate 1' polycarbonate substrate was prepared to have a diameter of 12 cm, an average thickness of 595.595 mm, and a continuous wobble groove (track gauge = 0.40 μηι) on one side. In the Ar gas air, the first lower protective layer 2a of 44 nm thick is plated with the magnetron of their sputtering target, and the -29-(26) (26) 1343050-recording layer 2b of 7.5 nm thick, 20 nm A thick first upper protective layer 2c' lOnm thick first reflective layer 2d, and a 25 nm thick thermal diffusion layer 2e are successively deposited on the polycarbonate substrate: ZnS (80)-SiO 2 (20 mol%) is used for the first The protective layer 2a, Ag〇.2In3.5Sb 6 9 8 Te22Ge4 5 is used for the first recording layer 2b > In2〇3 (7.5 mol%) -ZnO (22.5 mol%) -Sn02 (60 mol%) -Ta2 〇5 (l〇mol%) is used for the first upper protective layer 2c, Ag is used for the first reflective layer 2d, and In2〇3 (90 mol%)-ZnO (10 mol%) is used for the thermal diffusion layer 2e. As the second substrate 5, the polycarbonate substrate is prepared to have a diameter of 12 cm, an average thickness of 600600 mm, and a continuous oscillating groove on one side (gauge = 40.40 μιη). In Ar gas, With their sputtering The magnetron sputtering is performed by depositing a 140 nm thick second reflective layer 4d, a 22 nm thick second upper protective layer 4c, a 15 nm thick second recording layer 4b, and a 65 nm thick second lower protective layer 4a. On the polycarbonate substrate: AgBi (Bi = 0.5 wt%) is used for the second reflective layer 4d, and ZnS (80 mol%)-SiO2 (20 mol%) is used for the second upper protective layer 4c,

Ag〇 2In3.5Sb69 8Te22Ge4 5 is used for the second recording layer 4b, and ZnS (80 mol%) -SiO 2 (20 mol%) is used for the second lower protective layer 4a. The surface of the heat diffusion layer 2e is coated with a UV curable resin (KAYARADDO DVD003 M manufactured by NIPPON KAYAKU CO., LTD) and bonded to the second lower protective layer 4a. The intermediate layer 3 is formed by curing the UV curable resin by UV irradiation from the first substrate side to obtain a two-layer phase change optical disc having two information layers. It should be noted that the thickness of the intermediate layer 3 is set such that when the outer region is measured from the inner region of the disc, there is -30-(27) (27) 1343050 25 μηι ± 3 μϊη using the initialization device by the first substrate. The side is irradiated with a laser beam to initialize the second recording layer 4b and the first recording layer 2b. In the present initialization process, the laser beam from the semiconductor laser (oscillation wavelength = 8 10 ± l 〇 nm ) is focused by an objective lens into light spots on the respective recording layers. The initialization conditions for the second recording layer 4b are as follows: dish rotation = CLV (fixed linear velocity) mode; linear velocity = 3 m/s: pickup feed rate = 36 μm / rotation; radiation position (distance from the center of rotation) = 22-5 8 mm ; and initial power = 35 OmW. The initialization conditions for the first recording layer 2b are as follows: • Disc rotation = CLV (fixed linear velocity) mode: linear velocity = 5 m/s: pickup feed rate = 50 μm / rotation; radiation position (distance from the center of rotation) ) = 23-5 8 mm ; and initial power = 5 00 m W. The optical transmittance of the first information layer 2 after initialization is 40.1%. When the test is written, the first information layer is written to the first information layer 2 times Ttop = 0.30T, dTtop = 0.05T, Tmp^O^ST, and dTera = 0.0T. As a result, as shown in the graph of Fig. 10, the recording power (Pp) changes with the modulation (m). At this point, the bias power (Pb) is set to 〇.丨mW' and "ε" is set to 0.25. In addition, ytarget is set to 1.2. Moreover, the use of the tester to investigate the dependence of the PRSNR on the recording power in advance showed that the recording power providing the maximum PRSNR at this time was 9.5 mW, and the erasing power was 2.5 mW. Then, the 用于 for "P" is determined to be close to about 9.5 mW of recording power (Ppo). In particular, Ptarget is determined based on the previously selected Ytarget値, and a Ptarget of 7.55mW is obtained (see Figure 10). Next, according to -31 - (28) (28) 1343050, the Ptarget of 1.2 obtained above is regarded as the "p", so that the recording power (Ppo) is close to 9.5 mW. That is, Ppo is specified as 9 · 5 1 m W ( = 1. 2 6 X 7 · 5 5 ). As shown in Figure ', by changing the erase power (pe) with respect to the fixed recording power (Ppo) (= 9.5 mW), the PRSNR is calculated after 10 recording cycles to set various "ε" (=ρε/ρρο)値, The "ε" 提供 providing the maximum pRSNR 値 is 0.26. The Peo at this point is 2.5mW, which is almost the same as the 値 that was temporarily used. Thus, "ε" is set to 0.26. When it is decided on the recording device side, the 用于 for erasing power can be selected at the point where the ratio of the PRSNR change is flush. The asymmetry in this recording condition is as small as 〇. 〇 〇 5, which is almost zero. (Example 2) As in Example 1, the second information layer 4 of Example 1 determines the optimum laser beam power. In this example, the parameters of "γ" 値, "ρ" 値, "ε" 値, and the write strategy for each of the first and second information layers 2 and 4 are previously stored on the first substrate 1 side. The first information layer 2 is read into the area. When the test write is to be performed on the second information layer 4, the readout area (the periphery of the second information layer 4) or the read-in area of the second information layer 4 is selected. In this example, the readout area is written. Then, read "γ" from the disc is 1.5, "ρ" 値 is 1, 20, and "ε" 値 is 〇. 5, and the test is written with the following write strategy 1 write: Ttop = 0.5T 1 dTtop = 0T * Tmp = 0.4T, and dT era = -0.2T (where -0.2T means that the last Pb laser beam shown in Figure I is applied longer than 0.2T after the end of the data signal). As a result, the recording power (Pp) shows the modulation dependence as shown in Fig. 12 of -32-(29) (29) 1343050. As in Example 1, parget is 10.7mW and "p" is 12〇, and pp〇 is i2 84mW (=12〇 χ ι〇 7 ). That is, the optimum recording power (Ppo) is 12.85 mW. As shown in Fig. 113, by changing the erase power (Pe) with respect to the fixed optimum recording power (pp 〇) (= 12.85 mW), the PRSNR is calculated after 1 〇 recording cycle to set various "ε" (= Pe/Pp〇)値. The "ε" 提供 providing the maximum PRSNR値 is 〇.5. The peo at this point is 6.425mW. (Example 3) Using the optical recording medium identical to that of the example 1 prepared, the relationship between the modulation (m) of the first information layer 2 and the recording power (Pp) was investigated. Figure 14 illustrates this relationship. The ε of "ε" is set to 0.25. Therefore, when ytarget is set to 1.3, Ptarget値 is 8.33 mW. The plot of PRSNR vs. recording power shown in Figure 16. shows that the best recording power (Ppo) is 9.5 mW, so the “ of "p" is set to 1.14. In particular, the optimum recording power (Pp 〇) obtained from the above is equal to (P X Ptarget ), that is, 9.5 mW. As shown in Fig. 15, the PRSNR is then calculated after 2 recording cycles by changing the erase power (Pe) with respect to the fixed optimum recording power (Ppo) (= 9.5 mW) to set various "ε" (=Pe/ Ppo) 値. The "ε" 提供 providing the maximum PRSNR 値 is 0.275. The peo at this point is 2.52mW. From the above, "ε" is set to 0.275. (Example 4) -33- (30) (30) 1343050 The maximum PRSNR 获得 is obtained at "ε" = 0·265. It is effective to additionally use the asymmetry in the case where there is no change in the recording/regeneration device so that it is difficult to measure the PRSNR or have a large performance level change between the recording/reproducing devices. Figure 17 illustrates the asymmetry dependence on "ε" (=pe/ppo) after 2 recording cycles. The asymmetry 提供 that provides the maximum PRSNR値 is 0.0 04, which is almost zero. When the recording/reproducing device is to be used to determine the optimum erasing power, the specified asymmetry 値 "β" is used. Therefore, in addition to the write strategies ''ε', 'ytarget', 'Ptarget'', and 'ρ', the asymmetry β "β" is also stored as a necessary parameter in the first information layer 2. In this example "p" is set to 〇·〇〇. (Example 5) Using the optical recording medium identical to that of the example 1 prepared, the optimum recording condition for the first information layer 2 is determined, and then it is decided to use The optimum laser beam power of the second information layer 4. In this example, the laser beam with the best recording power is written in advance to the first information layer 2, and in the position corresponding to the recording area of the first information layer 2. Writes to the second information layer 4. Figure 18 illustrates the dependence of the modulation of the second information layer 4 on the recording power in this recording process. It is overwritten 10 times and has sample discs and overlays written to the first information layer. Write 1 time but not write to the first information layer comparison. The recording sensitivity between them has a difference of about 5.5mW; the one that is set to write the first information layer 2 shows poor recording sensitivity. In this case The recording sensitivity correction factor is added as a new parameter to enable To compensate for this difference, it is not necessary to write to the first information layer 2. Here, when the recording sensitivity is •·34- (31) (31) 1343050 13.5/13.0 (=1.04), the correction factor is 1.04» The power ratio or the difference in the obtained recording power is taken as another choice of the above correction factor. If the sensitivity difference is assumed to be 1.0 mm, then the equation Pp 〇 (the expected minimum power with L0 recording) = Pp 〇 (no L0 record) ) +1.0 mW to find the optimum recording power (Pp 〇). (Example 6) The optical recording mediums of the same example as those of the example 1 are written in the optimum recording power obtained in the examples 1 and 2, and The reflected signal voltage for the mark space between the longest marks is measured for each of the first and second information layers 2 and 4. Next, an Ag film is deposited on the glass substrate to a thickness of 200 nm using a sputtering apparatus to fabricate a dish. Using a media evaluation device, the laser beam is focused on a dish at a regenerative power of 0.7 m W to measure the reflected voltage. This reflected voltage is regarded as a 75% reflectance, and the reflectance of each information layer is calculated using the following equation ( R): R = 75 X (for the reflected voltage of each information layer) / ( The reflectance of the Ag film) The reflectance of the first information layer (R1) and the reflectance of the second information layer (R2) are 4.0% and 3.2%, respectively. Industrial applications are as described above to determine the optimum laser beam power. The method of the present invention is suitable for determining an appropriate laser beam power when recording on an optical disc having a plurality of rewritable recording layers. The optical recording medium of the present invention is suitable for stabilizing high quality recording. The program and method for performing the method of the present invention The storage medium for the storage program is -35- (32) 1343050. It is used to enable the optical disc device to perform stable high-quality recording on an optical recording disc having a plurality of rewritable recording layers. The single-sided double-layer disc of the present invention is a suitable disc for performing the method of the present invention. It is even possible to determine the optimum laser beam power for a disc having a single information layer by using the method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of φ of a pulse generation condition (write strategy) employed in the present invention. Figure 2 is a first diagram of recording power VS. modulation and γ値. Figure 3 is a second diagram of recording power VS. modulation and γ値. Figure 4 is a cross-sectional view showing the layer arrangement of the optical recording medium of the present invention. Figure 5 is a block diagram showing the configuration of a recording/reproducing apparatus used in the present invention. Figure 6 is a first flow diagram of the steps in the method of the present invention for determining optimum laser beam power. φ Figure 7 is a second flow diagram of the steps in the method of the present invention for determining the optimum laser beam power. Figure 8 is a graph of the erase power Pevs.PRSNR. Figure 9 is a graph of PRSNR versus number of overwrite cycles up to 10. Figure 10 is a plot of recording power vs. modulation and γ値 for Example 1. Figure 11 is a plot of Pe/Pp〇 vs. PRSNR after the 10 overwrite cycle of Example 1. Figure 12 is a graph of recording power vs. modulation and γ値 of Example 2. Figure 13 is a graph of Pe/Ppo vs. -36-(33) 1343050 PRSNR after the 10 recording cycle of Example 2. Figure 14 is a graph showing the recording power vs. modulation and γ値 of Example 3. • Figure 15 is a plot of Pe/Ppo vs., PRSNR after the recording cycle of Example 2, 2. Figure 16 is a graph of recording power vs. PRSNR. Figure 17 is a graph of the asymmetry of Pe/Ppo vs. of Example 4. Figure 18 is a graph of the recording power vs. modulation of Example 5. [Main component symbol description] 1 : First substrate 2 : First information layer 2 a : First lower protective layer 2 b : First recording layer 2 c : First upper protective layer ' 2d : First reflective layer • 2e : Thermal diffusion layer 3: intermediate layer 4: second information layer 4a: second lower protective layer • 4b: second recording layer • 4c: second upper protective layer 4d: reflective layer 5: second substrate 20: optical recording/reproducing device-37 - (34) 1343050

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Claims (1)

1343050 . 〇961〇6Π6 Patent Application Revision of Chinese Patent Application Scope I ~ ----j Republic 9 Hongfeng 〗 Moon Kiss 10, Application Patent Range----- 1. One determines the best laser a method of beam power for a single-sided, two-layer optical recording medium having first and second information layers, the method comprising: when the number of overwrite cycles on the recording medium is a predetermined time 'Determining the optimum laser beam power according to Φ predetermined characteristics, wherein the method is implemented by an optical recording/reproducing device using optical changes, wherein the first information layer is closer to the laser irradiation side than the second information layer , wherein the recording power is optimized according to the modulation of the longest mark between the marks of various lengths, and the cleaning power is optimized according to the PRSNR while using the optimum recording power as the fixed ,, and # The point at which the PRSNR or PRSNR change is flush with the erase power determines the optimum erase power. 2. A method of determining an optimum laser beam power according to the first aspect of the patent application, wherein the number of overwrite cycles on the recording medium is one. 3. The method of determining the optimum laser beam power according to the first aspect of the patent application, wherein the number of overwrite cycles on the recording medium is 10, which is the stability characteristic. 4. A method for determining an optimum laser beam power according to item 1 of the scope of the patent application, wherein the optimum erasing power is determined such that the asymmetry has a predetermined 値1343050. 5. The best ray according to the first item of the patent application scope A method of beam power, wherein an optimum laser beam power of the second information layer is determined in a state in which the first information layer is recorded after the optimal laser beam power of the first information layer has been determined. 6. An optical recording medium comprising: a recording sensitivity correction factor 'this factor enables the method of determining the optimum laser beam power according to item 5 of the scope of the patent application, which can be determined without writing to the first information layer The optimum laser beam power of the second information layer. 7. An optical recording medium comprising: information required to perform the method of determining the optimum laser beam power according to item 1 of the scope of the patent application. 8 _ The optical recording medium according to claim 7, wherein the first and second information layers corresponding to the position of the user data area have a reflection ratio of 3% to 6%. -2-